Whey protein isolate (WPI) is the holy grail of protein powders, most pure form of whey protein available. Whey protein isolate has the highest amount of pure protein, typically containing around 85% to 98% pure protein. Not only whey protein isolate the most pure form of protein, but it also has the highest biological value (BV). Biological value is a measure of how fast your body can use a fuel source.

Whey protein isolate is great for both fat loss and muscle gain. Out of all the protein whey sources, isolate has the lowest amount of fat and lactose.